1. Field of the Invention
The invention in general relates to hydrophones, and more particularly to a hydrophone designed for listening to extremely low frequency acoustic waves.
2. Description of the Prior Art
A hydrophone is a device that responds to water-borne sound waves and delivers essentially equivalent electric waves. Such hydrophones find extensive use in the underwater environment for listening to very low frequency noise as may be produced, for example, by submarines or surface vessels.
In use, one or more hydrophones may be suspended, by a supporting cable for example, in the water medium to monitor the vehicular traffic. The design of some hydrophones, however, is such that when the hydrophone itself is accelerated due to movement of the supporting cable, an output signal is provided which is not related to any impinging low frequency acoustic waves, but instead is due to the acceleration of the unit.
A need exists for a relatively inexpensive simply constructed hydrophone which can endure the rigors of an underwater environment. Moreover, the hydrophone must be designed to respond to extremely low frequency acoustic waves and to be nonresponsive to physical movement of the hydrophone itself.